For cathode active materials for lithium ion batteries, lithium-containing transition metal oxides are usually used. The lithium-containing transition metal oxides are specifically lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium manganate (LiMn2O4), and the like, and making these into a composite has been progress in order to improve properties (capacity enhancement, cycle properties, preservation properties, internal resistance reduction, and rate characteristic) and enhance safety. For lithium ion batteries in large-size applications as for vehicles and road leveling, properties different from those for cellular phones and personal computers hitherto are demanded.
For the improvement of battery properties, various methods have conventionally been used, and for example, Patent Literature 1 discloses a production method of a cathode material for a lithium secondary battery, in which method a lithium nickel composite oxide represented by a composition ofLixNi1−yMyO2−δwherein 0.8≦x≦1.3 and 0<y≦0.5; M denotes at least one element selected from the group consisting of Co, Mn, Fe, Cr, V, Ti, Cu, Al, Ga, Bi, Sn, Zn, Mg, Ge, Nb, Ta, Be, B, Ca, Sc, and Zr; and δ corresponds to an amount of oxygen deficiency or an amount of oxygen excess, and −0.1<δ<0.1 is passed through a classifying machine to be separated into the oxide having large particle diameters and the oxide having small particle diameters at an equilibrium separation particle diameter Dh of 1 to 10 μm, and the oxide having large particle diameters and the oxide having small particle diameters are blended at a weight ratio of 0:100 to 100:0. Then, the Patent Literature states that a cathode material for a lithium ion battery having various balances between rate characteristic and capacity can easily be produced.